sendmail Features

The sendmail program
provides the following features.

sendmail is reliable. The program is designed
to correctly deliver every message. No message should ever become completely
lost.

sendmail uses existing software for delivery
whenever possible. For example, the user interacts with a mail-generating
and a mail-sending program. When mail is submitted, the mail-generating program
calls sendmail, which routes the message to the correct
mailers. Because some of the senders might be network servers and some of
the mailers might be network clients, sendmail can be used
as an Internet mail gateway. See Interactions of Mail Programs for a more detailed description of the process.

sendmail can be configured to handle complex
environments, including multiple networks. sendmail checks
the contents of an address as well as its syntax to determine which mailer
to use.

sendmail uses configuration files to control
mail configuration instead of requiring that configuration information be
compiled into the code.

Users can maintain their own mailing lists. Additionally,
individuals can specify their own forwarding mechanism without modifying the
domain-wide alias file, typically located in the domain-wide aliases that
are maintained by NIS or NIS+.

Each user can specify a custom mailer to process incoming mail.
The custom mailer can provide functions such as returning a message that reads: “I
am on vacation.” See the vacation(1) man page for more information.

sendmail batches addresses to a single
host to reduce network traffic.